Selective Non-Catalytic Reduction (SNCR) uses similar chemical reducing agents (ammonia/urea) as SCR but without a catalyst reactor.
To achieve chemical reduction of NOx without a catalyst, a higher temperature environment is needed. Selective non-catalytic reduction (SNCR) require the ammonia/urea solution to be injected into the flue gas system at temperature of about 1000°C.
Position and attitude of ammonia injection ports, as well as nozzle design, is important to achieve optimum droplet size and mixing of ammonia/urea reagent with the furnace gases.
Multiple injection ports, to accommodate furnace temperature changes with boiler load, can be fitted to allow injection of reagent into the optimum temperature zone under all firing conditions.
This can include injection into the furnace and superheater sections with boiler lead/temperature control of reagent injection. This not only maintains NOx removal efficiency but also minimises reagent slippage to atmosphere.